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Anal Stenosis

What is anal stenosis?

When a tubular organ or blood vessel, or tubular organ becomes excessively narrow, such that it can no longer perform as nature intended, it is a condition referred to by physicians as stenosis. Anal stenosis, also known as an anal stricture, is the narrowing of the anal canal, located just before the anal sphincter.

What is the anal sphincter?

The anal sphincter is a complex part of the body that maintains a seal that can be opened to discharge body waste. It is strong enough to restrict the passage of any fecal material but sensitive enough to differentiate between solid, liquid, and gas. There are actually two anal sphincter muscles … the internal anal sphincter and the external anal sphincter.

illustration of anal canal indicating internal and external anal sphincter

The internal anal sphincter is a thin, white muscle wrapped around the anal canal. The internal sphincter contracts during rest and sleep, and keeps small amounts of liquid and gas from escaping unexpectedly. The internal anal sphincter is an involuntary smooth muscle, like the muscles of your intestines. You cannot mentally control it.

The external anal sphincter is a thick, red voluntary muscle. It is wrapped around the internal anal sphincter muscle. It is the one you squeeze when you feel the urge to go to the bathroom but are not near one. Since it is voluntary muscle, like the muscles in your arms and legs, you can control it.

When food waste reaches the anus, it begins collecting in the flexible rectum. When enough waste has collected, a person will feel the need to go to the bathroom. Once the person is seated on the toilet, the anal sphincter should relax and allow the anal canal to empty. When the waste has been released from the canal, the anal sphincter should restrict and remain in that condition until the process needs to occur again.

But there can be problems … and one of those problems is called anal stenosis. Anal stenosis is a serious condition that can greatly impact a person's lifestyle and total well-being.

What causes anal stenosis?

Anal stenosis can be the result of many things, such as:

There is a condition known as Anal Crohn's disease that mimics the symptoms of anal stenosis. Crohn's disease is an inflammation that can restrict the anal canal.


Symptoms can vary depending on the severity of the stenosis. They may include:

Treatment of anal stenosis

a male physician speaking with an older female patient

Fortunately, preventing the condition from even occurring is the best treatment. But that is not always an option, especially if you must undergo surgery.

Some common preventative measures are:

Surgical procedures to alleviate anal stenosis

The procedure that is performed to relieve anal stenosis is called an anoplasty. There are many variations of this procedure, and one is selected depending on the size and structure of the stenosis.

After surgery

Things to remember

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Why should I visit the Medical University of South Carolina?

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MUSC Ashley River Tower

Your doctor will probably agree with you about your preference to come to MUSC. We offer excellent patient care at a state-of-the-art facility, in a historic setting in the southeastern United States. Our doctors are nationally ranked among the highest in the nation. We employ a multidisciplinary approach to the treatment of patients using the latest technology in medicine.

Come see why MUSC is changing what's possible®.

Read more about why you should choose MUSC for your healthcare needs.